Saturday, January 20, 2018

Mosses of Central Florida 43. Micromitrium

There are three species of Micromitrium (Ephemeraceae) in our area: M. megalosporum Austin
Micromitrium tenerum at a drying pond edge.  Permission pending from
Okayama University of Science,
M. tenerum (Bruch & Schimp.) Crosby and M. synoicum (James) Austin.  These are tiny short-lived plants that form sparse colonies on bare soil along drying pond edges.  The plants form rosettes with a single, globose sporangium nestled among the leaves.  Their leaves lack a midrib and the leaf cells are elongate, somewhat curved (worm-like) and smooth.

They are similar to Ephemerum crassinervium, which is in the same family, but that species has leaves with  distinct midribs, more ovoid capsules, and papillose cells near the tip of the leaf.

The ranges of the three species overlap, as they all occur throughout eastern North America. M. tenerum has been also reported from British Columbia, and M. synoicum from Oregon.  In Florida, they are all found primarily in the panhandle region, with reports from as far south as Polk County. None are collected very often, however, as they are short-lived and hard to see.

In M. megalospermum the leaves are broadly ovate and the spore capsule opens irregularly, while in M. synoicum and M. tenerum the leaves are lance-shaped, and the capsules open along a distinct ring around the middle or above.

In M. synoicum the leaves are erect, with smooth, somewhat incurved margins and have distinct stems below the crown of leaves, while in M. tenerum the leaves are spreading, with flat margins, and teeth at the tips, and the plants are stemless.

Thursday, January 11, 2018

Mosses of Central Florida 42. Papillaria nigrescens

Papillaria nigrescens (Hedwig) A. Jaeger (Meteoraceae) occurs on tree bark in shaded, humid hammocks.  It's leaves are scale-like and pressed against the stem, giving the yellowish to blackish leafy shoots the appearance of tiny juniper twigs.  Some shoots have drooping, whip-like extensions with sparser, smaller leaves, or are nearly naked with a small tuft of leaves at the ends.  This species is not known to produce spore capsules in our area.
Dried specimen of Papillaria nigrescens, collected in Hillsborough River State Park on bark of hardwood tree (Griepenburg 10, USF) 

The main leaves are ovate, but gradually narrowing to a sharp tip.  Leaf cells are narrowly-ovate and tapered, and somewhat wavy (worm-like) with papillae (hard, translucent bumps). The midrib reaches to about mid-leaf, though may not be very distinct.
The scale-like leaves of Papillaria gradually taper to a sharp
tip. A faint midrib extends a little more than half the leaf

This species has been found throughout Florida, but collected only occasionally.  It occurs throughout the New World tropics, and elsewhere in the U.S. it has only been found in southern Louisiana. It has previously been known as Meteorium nigrescens.
Leaf cells in Papillaria are elongate, tapered and somewhat wavy.  The papillae (hard, translucent dots) can be seen lined up along the length of each cell.

Tuesday, January 9, 2018

Mosses of Central Florida 41. Tortella

The genus Tortella (Pottiaceae) includes two species found in Florida.  The genus is distinguished from other members of the family, such as Barbula or Hyophiladelphus by the distinctive V- or U-shaped boundary between the large basal region of clear cells and the upper green cells.  It shares with them the elongate leaves with strong midrib, and the upright spore capsules with long twisted teeth around the opening.  Leaf cells in the upper part of the leaf are small, round and papillose.
Leaves of Tortella densa illustrate the distinctive leaves of the genus.  Note the V-shaped boundary between the large clear cells at the base and the smaller green cells of the tip.  Photo by Hermann Schachner, posted on Wikimedia, Creative Commons license.
The long, twisted teeth around the opening
of the spore capsule, characteristic of
Tortella and several other genera of the
Pottiaceae.  Photo courtesy the Western
New Mexico University, Department of
Natural Sciences and the Dale A.
Zimmerman Herbarium,
Plants of the Gila Wilderness.

Tortella flavovirens (Bruch) Brotherus and T. humilis Hedwig both form low colonies of upright leafy shoots, with leaves distributed uniformly around the stem (radially symmetrical).  Capsules arise from the tips of the shoots. In T. humilis the stems are  elongate, forming loose tufts, while in T. flavovirens, they are more compact, forming dense mats of rosettes.

In Florida, both species occur scattered throughout the state. Tortella humilis is found throughout eastern North America and in scattered mountain locations from New Mexico to British Columbia. It is found inland on soil, tree bases, and rocks. T. flavovirens has a more southern distribution, from Texas to North Carolina. It is tolerant of salt spray and is confined to coastal vegetation.